A trivalent inactivated PDCoV-PEDV-TGEV vaccine confers protective efficacy in piglets coinfected with porcine rotavirus.

Porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV), and transmissible gastroenteritis virus (TGEV) are the primary enteric coronaviruses responsible for viral diarrhea in piglets. These pathogens frequently co-circulate with porcine rotavirus (PoRV) under field conditions, leading to increased disease severity and complicating prevention efforts. Although multivalent vaccines targeting these three coronaviruses have been developed, their protective efficacy in the presence of PoRV coinfection remains largely unknown. Based on our previously developed trivalent inactivated PDCoV-PEDV-TGEV vaccine, the present study evaluated its immunoprotective efficacy in piglets naturally infected with PoRV. The results showed that, despite the background of persistent PoRV infection, the trivalent vaccine induced detectable neutralizing antibodies against PEDV, PDCoV, and TGEV (titers≥1:64). Furthermore, vaccination significantly reduced fecal viral shedding after challenge, shortened the duration of diarrhea, and alleviated intestinal pathological damage. Immunofluorescence assays confirmed that antigen deposition of the target coronaviruses in the intestines of vaccinated piglets was markedly reduced. However, vaccinated piglets continued to shed PoRV, indicating that the vaccine did not confer sterilizing immunity but rather reduced clinical severity. This study provides the experimental evidence that the trivalent inactivated vaccine confers effective protection against the three major porcine enteric coronaviruses even under complex clinical conditions involving PoRV coinfection. These findings offer important insights for developing immunization strategies to control multi-pathogen infections in swine production.